Clean Fill Port System and Method

ABSTRACT

A clean fill port system for a compressed gas tank having a fill port includes a sealable enclosure surrounding the fill port. The sealable enclosure includes a closeable lid that defines a sealed cavity within the sealable enclosure when the lid is in a closed position. A pressurized fluid supply port is directly fluidly connected with the sealed cavity. The sealable enclosure completely encloses the fill port and is configured to maintain a pressurized fluid within the sealed cavity such that ingress of water or debris into the sealed cavity is prevented.

TECHNICAL FIELD

This patent disclosure relates generally to enclosures and, more particularly, to an enclosure for a fuel port of a compressed gas tank.

BACKGROUND

Self-propelled vehicles having prime movers that use fuel during operation typically carry on-board fuel reservoirs. Fuel from the reservoir is used by the engine and is periodically replenished. Depending on the type of fuel used in the vehicle, fuel replenishment can be carried out through a port or other passageway that interconnects the fuel reservoir with an access point on the vehicle that is accessible by the operator. For example, vehicles using liquid fuels at atmospheric pressure such as gasoline or diesel may have a fill-port connected to a fuel tank. The fill-port may be located at a convenient location on the vehicle to ease the fuel filling operation. The fill-port typically includes a removable cap, which can substantially fluidly block the fill port during normal service so that fuel evaporation or fuel contamination from debris entering the fuel tank through the fill-port is avoided. Certain vehicles may further include fill-port and cap covers, mostly for aesthetic purposes.

In typical vehicle applications, the fuel reservoir is prone to water or debris ingress then the cap is removed for refueling. This is usually not a serious issue for vehicle operation because most vehicles carry on-board fuel filtering and other conditioning devices, for example, water separators, which can effectively remove water and other debris that may have contaminated the fuel before the water or other contaminants reach the engine.

However, certain types of fuel cannot be easily filtered and/or conditioned to remove water due to their nature or temperature. For example, liquefied natural gas (LNG) burning vehicle engines are typically supplied from an LNG tank, which stores the LNG as a liquid at a cryogenic state. As can be appreciated, water contamination of the LNG cannot be easily addressed due to the low storage temperature of the LNG. Moreover, filtering of LNG while in the liquid state presents challenges and cannot be easily accomplished on-board a vehicle. LNG storage tanks carried on vehicles include specialized fill-ports that are prone to water or debris ingress during refueling operations. Issues with fuel contamination are especially prevalent in certain applications where the vehicles may be covered in dirt or mud such as in mining applications, or for marine applications where fuel contamination with water during refueling is possible.

SUMMARY

The disclosure describes, in one aspect, a clean fill port system for a compressed gas tank. A fill port of the compressed gas tank is surrounded by a sealable enclosure, which includes a closeable lid that defines a sealed cavity within the sealable enclosure when the lid is in a closed position. A pressurized fluid supply port is directly fluidly connected with the sealed cavity. The sealable enclosure completely encloses the fill port and is configured to maintain a pressurized fluid within the sealed cavity such that ingress of water or debris into the sealed cavity is prevented.

In another aspect, the disclosure describes an engine system that includes a compressed gaseous fuel tank that contains gaseous fuel used to operate an engine. The compressed gaseous fuel tank includes a fill port providing access for refueling of the compressed gaseous fuel tank. A sealable enclosure surrounds the fill port, and includes a closeable element that defines a sealed cavity within the sealable enclosure when the closeable element is in a sealed position. A pressurized fluid supply port that is directly fluidly connected with the sealed cavity is configured to provide a compressed fluid to fill and pressurize the sealed cavity when the closeable element is in the sealed position. The sealable enclosure completely encloses the fill port and is configured to maintain a compressed fluid within the sealed cavity in a pressurized condition during operation of the engine such that ingress of water or debris into the sealed cavity is prevented.

In yet another aspect, the disclosure describes a method for preventing contamination of a compressed gas kept in a compressed gas tank with water or other debris entering into the tank through a tank fill port during a tank filling operation. The method includes enclosing a fill port of a compressed gas tank within an enclosure extending at least around a fill portion of the fill port. An internal cavity of the enclosure is pressurized with fluid. The internal cavity of the enclosure is maintained in a pressurized condition such that ingress of debris into the internal cavity is discouraged. The enclosure is opened such that the internal cavity is depressurized before carrying out a tank filling operation. After the tank filling operation is complete, the enclosure is closed and the internal cavity of the enclosure is re-pressurized with fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an engine system having a compressed gas fuel system that includes a gaseous fuel storage tank in accordance with the disclosure.

FIGS. 2 and 3 are partial views of a gaseous fuel tank fill port in accordance with the disclosure.

FIG. 4 is a cross section of an enclosure for a fill port of a gaseous fuel tank in accordance with the disclosure.

FIG. 5 is a flowchart for a method in accordance with the disclosure.

DETAILED DESCRIPTION

This disclosure relates to engines using a gaseous fuel source such as direct injection gas (DIG) or indirect injection gas engines using diesel or spark ignition. More particularly, the disclosure relates to an embodiment for an engine system that includes a gaseous fuel storage tank having a sealed fill port for avoiding contamination of the gaseous fuel during refueling operations with foreign matter such as water, dirt, and other debris. A block diagram of a DIG engine system 100, which in the illustrated embodiment uses diesel as the ignition source, is shown in FIG. 1. The engine system 100 includes an engine 102 (shown generically in FIG. 1) having a fuel injector 104 associated with each engine cylinder 103. The fuel injector 104 can be a dual-check injector configured to independently inject predetermined amounts of two separate fuels, in this case, diesel and gas, into the engine cylinders.

The injector 104 is connected to a high-pressure gaseous fuel supply line 108 and to a high-pressure liquid fuel rail 110 via a liquid fuel supply line 112. In the illustrated embodiment, the gaseous fuel is natural or petroleum gas that is provided through the gaseous fuel supply line 108 at a pressure of between about 10-50 MPa, and the liquid fuel is diesel, which is maintained within the liquid fuel rail 110 at about 15-100 MPa, but any other pressures or types of fuels may be used depending on the operating conditions of each engine application. It is noted that although reference is made to the fuels present in the supply line 108 and the fuel rail 110 using the words “gaseous” or “liquid,” these designations are not intended to limit the phase in which is fuel is present in the respective rail and are rather used solely for the sake of discussion of the illustrated embodiment. For example, the fuel provided at a controlled pressure within the gaseous fuel supply line 108, depending on the pressure at which it is maintained, may be in a liquid, gaseous or supercritical phase. Additionally, the liquid fuel can be any hydrocarbon based fuel; for example DME (Dimethyl Ether), biofuel, MDO (Marine Diesel Oil), or HFO (Heavy Fuel Oil).

Whether the system 100 is installed in a mobile or a stationary application, each of which is contemplated, the gaseous fuel may be stored in a liquid state in a cryogenic tank 114, which can be pressurized at a relatively low pressure, for example, atmospheric, or at a higher pressure. In the illustrated embodiment, the tank 114 is insulated to store liquefied natural gas (LNG) at a temperature of about −160° C. (−256° F.) and a pressure that is between about 100 and 1750 kPa, but other storage conditions may be used. The tank 114 further includes a pressure relief valve 116 and a fill port 144. The fill port 144 may include special or appropriate features for interfacing with a compressed natural gas (CNG) and/or liquid petroleum gas (LPG) fill hose or valve. In the description that follows, a DIG engine system embodiment is used for illustration, but it should be appreciated that the systems and methods disclosed herein are applicable to any machine, vehicle or application that uses cryogenically stored gas.

Relative to the particular embodiment illustrated, during operation, LNG from the tank is compressed, still in a liquid phase, in a pump 118, which raises the pressure of the LNG while maintaining the LNG in a liquid phase. The pump 118 is configured to selectively increase the pressure of the LNG to a pressure that can vary in response to a pressure command signal provided to the pump 118 from an electronic controller 120. Although the LNG is present in a liquid state in the tank, the present disclosure will make reference to compressed or pressurized LNG for simplicity when referring to LNG that is present at a pressure that exceeds atmospheric pressure.

Accordingly, the compressed LNG is heated in a heat exchanger 122. The heat exchanger 122 provides heat to the compressed LNG to reduce density and viscosity while increasing its enthalpy and temperature. In one exemplary application, the LNG may enter the heat exchanger 122 at a temperature of about −160° C., a density of about 430 kg/m³, an enthalpy of about 70 kJ/kg, and a viscosity of about 169 μPa s as a liquid, and exit the heat exchanger at a temperature of about 50° C., a density of about 220 kg/m³, an enthalpy of about 760 kJ/kg, and a viscosity of about 28 μPa s. It should be appreciated that the values of such representative state parameters may be different depending on the particular composition of the fuel being used. In general, the fuel is expected to enter the heat exchanger in a cryogenic, liquid state, and exit the heat exchanger in a supercritical gas state, which is used herein to describe a state in which the fuel is gaseous but has a density that is between that of its vapor and liquid phases. The heat exchanger 122 may be any known type of heat exchanger or heater for use with LNG. In the illustrated embodiment, the heat exchanger 122 is a jacket water heater that extracts heat from engine coolant. In alternative embodiments, the heat exchanger 122 may be embodied as an active heater, for example, a fuel fired or electrical heater, or may alternatively be a heat exchanger using a different heat source, such as heat recovered from exhaust gases of the engine 102, a different engine belonging to the same system such as what is commonly the case in locomotives, waste heat from an industrial process, and other types of heaters or heat exchangers. In the embodiment shown in FIG. 1, which uses engine coolant as the heat source for the heat exchanger 122, a temperature sensor 121 is disposed to measure the temperature of engine coolant exiting the heat exchanger 122 and provide a temperature signal 123 to the controller 120.

Liquid fuel, or in the illustrated embodiment diesel fuel, is stored in a fuel reservoir 136. From there, fuel is drawn into a variable displacement pump 138 through a filter 140 and at a variable rate depending on the operating mode of the engine. The rate of fuel provided by the pump 138 is controlled by the pump's variable displacement capability in response to a command signal from the electronic controller 120. Pressurized fuel from the pump 138 is provided to the liquid fuel rail 110.

Gas exiting the heat exchanger 122 is filtered at a filter 124. As can be appreciated, the gas passing through the filter 124 may include gas present in more than one phase such as gas or liquid. Considering that gas at different phases may have different viscosity and/or density, the filter 124 may not always be sized appropriately to effectively remove solid contaminants from the gas such as dirt. In the event dirt or other debris is passed to the fuel injectors 104 during operation, depending on the particle size and hardness of the debris, damage may occur at the fuel injectors 104 and/or to other fuel system components, for example, the pump 118. Moreover, given that the gas is substantially heated before it is filtered, any water present within the tank 114 may be in a solid state and thus may not be removed from the gas at the filtering or other conditioning stages.

One embodiment for an LNG-powered application is shown in FIGS. 2 and 3, where an on-highway truck 200 is partially illustrated. Here, the truck 200 includes a fuel tank 202 disposed on a side of the frame thereof. The fuel tank 202 as shown is the tank 114 (FIG. 1), which is configured to cryogenically contain and store gaseous fuel. The placement of the fuel tank 202 on the truck 200 is such that the tank 202 is exposed to the elements as well as to road grime and debris, rain, snow, ice, road salt, chemicals, pressure washing, and the like. The fuel tank 202 has a fill port 204 that is located at an end thereof and, as shown, is sloped downward to avoid water accumulation therein. However, when the fill port 204 is exposed to the elements contaminants such as dirt, water and other debris may collect in and around the fill port 204. The presence of contaminants in and around the fill port 204 increases the likelihood that those contaminants may enter the interior of the tank 202 and contaminate the fuel stored therein.

To avoid or at least partially mitigate the issue of fuel contamination during fuel fill-up operations, the tank 114 (FIG. 1) includes an enclosure 206 disposed around the fill port 144. A detailed cross section of the enclosure 206 is shown in FIG. 4. The enclosure 206 includes a cavity 208 that, in the illustrated embodiment, is defined within a wall 210 that is connected to an outer shell 212 of the tank 114. The outer shell 212 of the tank is disposed around an inner shell 213 at a distance such that a gap 215 is formed therebetween. The gap 215 is typically fluidly isolated and exposed to vacuum to provide thermal insulation to the contents of the tank 114 from the environment.

The enclosure wall 210 surrounds the fill port 144 and also encloses a portion of the outer shell 212 disposed around the fill port 144. A lid 214 sealably engages the wall 210 to further define the cavity 208, which in the illustrated embodiment completely encloses the fill port 144 and the portion of the outer shell 212 of the tank 114 that surrounds the port 144. Although the lid 214 is shown as being flat, it may alternatively have a cupped-shape that at least partially defines the cavity 208, or may alternatively be dome-shaped.

A seal 216, which in FIG. 4 is embodied as an o-ring, is disposed to fluidly seal an interface between the lid 214 and enclosure wall 210 such that the cavity 208 can retain a positive (or negative) gauge pressure relative to the surrounding environment. As previously discussed, the fill port 144 includes a check valve 218 that allows for fuel entry into a tank interior volume 220 during refueling, but otherwise contains the tank's contents within the tank interior 220.

During operation of the engine system 100 (FIG. 1), pressurized fluid is provided to fill the cavity 208 and maintain therein a positive gauge pressure with respect to the surrounding external environment. The positive gauge pressure within the cavity 208 provides a barrier against ingress of water, debris and/or other contaminants into and around the fill port 144. Moreover, pressurized fluid to fill the cavity 208 is provided systematically during operation of the system 100 such that any leakage of fluid out from the cavity 208 or the loss of pressure within the cavity 208 when the lid 214 is opened to refill the tank 114 are compensated. When refilling the tank 114, for example, the lid 214 is opened, as shown with dotted line in FIG. 4, such that a fuel spout 222 can connect to the fill port 144. When the refueling operation is completed, the fuel spout 222 is removed and the lid 214 restored to its closed position. At this time, the cavity 208 has depressurized by the opening of the lid 214, and is re-pressurized as described in further detail below.

In reference now to FIG. 3, three different embodiments for providing a pressurized fluid to fill the cavity 208 (FIG. 4) are shown. At least one of the three fluid sources of pressurized fluid shown in FIG. 1 or different fluid sources may be used in an application depending on the system components and systems that are available to provide the pressurized fluid.

In a first embodiment, the pressurized fluid provided to the cavity 208 is gaseous fuel from within the tank, which is provided through the pressure relief valve 116. In this embodiment, gaseous fuel under pressure that would have otherwise been vented from the tank 114 is used to pressurize the cavity 208. More specifically, a gas passage 302 is fluidly connected to the interior of the tank 114. The gaseous fuel within the tank 114 may be at a relatively high pressure, for example, of about 150 psi, which may be too high for use to pressurize the cavity 208. For this reason, an optional pressure regulator 304 may be used to regulate the pressure of gas provided to the cavity to 1 or 2 psi. The gas passage 302 is shown in dashed line to denote that it represents one of three embodiments shown in FIG. 1.

In a second embodiment, the pressurized fluid provided to the cavity 208 is compressed air from an auxiliary air compressor 306 that is powered by the engine 102. In certain applications, such as on- and off-highway trucks, locomotives and the like, auxiliary pressurized air systems are used to operate pneumatic systems such as brakes and other actuators. In such systems, an air compressor, for example, the air compressor 306, is typically provided that is powered directly or indirectly by the engine. In the illustrated embodiment, the air compressor 306 is driven by a gear system 310 that is associated with an output shaft 312 of the engine 102. The air compressor 306 provides compressed air to a reservoir or tank 308, which in turn supplies compressed air to other systems. In this embodiment, a compressed auxiliary air conduit 314 is fluidly connected with an outlet of the compressor 306 and includes a check valve 316, which may further include a pressure regulator function. In this arrangement, pressurized air from the auxiliary compressor 306 is provided to the cavity 208 at a controlled pressure. Further, the check valve 316 can help maintain pressure within the cavity 208 when the engine 102 and, thus, the compressor 306 are not operating.

In a third embodiment, the pressurized fluid provided to the cavity 208 is compressed air from an engine intake system compressor 318. More specifically, the engine 102 in this embodiment includes an exhaust collector 320 that provides pressurized exhaust gas to at least one turbine 322. The turbine 322 is part of a turbocharger 324, which also includes the turbine-driven compressor 318 configured in the known fashion. In an alternative embodiment, the compressor 318 may be a supercharger that is mechanically, electrically or otherwise driven.

In the third embodiment, air from an intake air filter 326 is provided to the compressor 318 where it is compressed into an engine intake charge. The intake charge is provided to an intake collector such as an intake manifold 328. Between the compressor 318 and intake manifold 328, a charge air cooler 330 may be used to cool the intake charge before it is provided to the engine cylinders 103. An engine compressed air conduit 332 is fluidly connected with the outlet of the compressor 318 to provide a portion of the air charge, for example, 1 or 2%, to the cavity 208 during engine operation. The compressed air conduit 332 may optionally be connected downstream of the charge air cooler 330 and may further include a check valve 334, which may also include a pressure regulator function.

In the illustration of FIG. 1, at least one of the gas passage 302, auxiliary air conduit 314, or charge air conduit 332, may be connected to a pressure conduit 336 that is fluidly open to the cavity 208, as shown in FIG. 4. In reference to FIG. 4, it can be seen that a pressurized fluid provided at the pressure conduit 336 will fill, occupy and pressurize the internal volume of the cavity 208 around the fill port 144 while the lid 214 is closed. This fluid pressurization within the cavity 208 will create a pressurized fluid barrier against ingress of water or debris within the cavity 208 such that the fill port 144 can be maintained clean between refueling operations. Various additional measures can be taken to ensure that the function of the enclosure 206 is utilized by all operators. Two such embodiments are shown in FIG. 4. In a first embodiment, a pressure switch or sensor 338 is disposed to sense the closed position of the lid 214 onto the wall 210 that seals the enclosure 206. Here, a position signal 340 indicating that the lid is open (or closed), can be provided to the controller 120 (also shown in FIG. 1) or to another controller. Alternatively or additionally, a fluid pressure sensor 342 may be associated with the cavity 208 and disposed to measure a fluid pressure therein. The fluid pressure sensor 342 may provide a pressure signal 344 indicative of the fluid pressure within the cavity 208 during operation to the electronic controller 120 or to another controller.

The controller, based on the position signal 340 and/or the pressure signal 344 may take appropriate action in the event the enclosure is left open or cannot pressurize during operation such that contamination of the fill port 144 can be avoided. For example, the controller may cause a visual and/or audible notification to be provided to an operator if it is determined that the lid 214 has been left open or not properly closed. Alternatively, an interlock system may prevent engine start or vehicle motion under such conditions. The controller may also set a failure flag when it is determined that insufficient sealing pressure is present within the cavity during operation as an indication that service or a diagnosis of the condition of the system is required.

INDUSTRIAL APPLICABILITY

The present disclosure is applicable to any type of application that involves a compressed gas storage tank. In the illustrated embodiment, a land vehicle having a CNG or LPG fuel source that is carried in an on-board tank was used for illustration, but those of ordinary skill in the art should appreciate that the methods and systems described herein have universal applicability to any type of fill port for a compressed gas tank.

A flowchart for avoiding contamination of a compressed fluid kept in a tank during a tank filling operation is shown in FIG. 5. The process includes enclosing a fill port at 402 within an enclosure extending around a fill portion of fill port. An internal cavity of the enclosure is pressurized with a fluid at 404, and maintained at a pressurized condition at 406 while no filling operation is to be carried out. The cavity is depressurized and opened at 408 before a filling operation is carried out. The filling operation is carried out at 410, and the enclosure is resealed at 412 following completion of the filling operation. The internal cavity of the enclosure is re-pressurized at 414 and the process is repeated for each subsequent filling operation.

It will be appreciated that the foregoing description provides examples of the disclosed system and technique. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the disclosure entirely unless otherwise indicated.

Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. 

We claim:
 1. A clean fill port system for a compressed gas tank, the gas tank having a fill port, the clean port system comprising: a sealable enclosure surrounding the fill port, the sealable enclosure including a closeable lid that defines a sealed cavity within the sealable enclosure when the lid is in a closed position; a pressurized fluid supply port that is directly fluidly connected with the sealed cavity; wherein the sealable enclosure completely encloses the fill port and is configured to maintain a pressurized fluid within the sealed cavity such that ingress of water or debris into the sealed cavity is prevented.
 2. The clean fill port system of claim 1, wherein the compressed tank includes an outer shell, and wherein the sealable enclosure includes a wall connected to the outer shell and disposed around the fill port, the wall having a sufficient dimension to completely enclose the fill port when the closeable lid is in the closed position.
 3. The clean fill port system of claim 2, further comprising a seal disposed along an interface between the wall and the closeable lid.
 4. The clean fill port system of claim 1, further comprising a sensor disposed to sense and provide a position signal indicative of the closed position or an open position of the lid to an electronic controller.
 5. The clean fill port system of claim 1, further comprising a sensor disposed to sense and provide a pressure signal indicative of a fluid pressure within the sealed cavity to an electronic controller.
 6. An engine system that includes a compressed gaseous fuel tank provided to operate an engine, comprising: a fill port providing access for refueling of the compressed gaseous fuel tank; a sealable enclosure surrounding the fill port, the sealable enclosure including a closeable element that defines a sealed cavity within the sealable enclosure when the closeable element is in a sealed position; a pressurized fluid supply port that is directly fluidly connected with the sealed cavity and configured to provide a compressed fluid to fill and pressurize the sealed cavity when the closeable element is in the sealed position; wherein the sealable enclosure completely encloses the fill port and is configured to maintain a compressed fluid within the sealed cavity in a pressurized condition during operation of the engine such that ingress of water or debris into the sealed cavity is prevented.
 7. The engine system of claim 6, wherein the compressed gaseous fuel tank includes an outer shell, and wherein the sealable enclosure includes a wall connected to the outer shell and disposed around the fill port, the wall having a sufficient dimension to completely enclose the fill port when the closeable element is in the sealed position.
 8. The engine system of claim 7, further comprising a seal disposed along an interface between the wall and the closeable element, the seal configured to prevent leakage of the compressed fluid from within the sealed cavity when the closeable element is in the sealed position.
 9. The engine system of claim 6, further comprising a position sensor disposed to sense and provide a position signal indicative of the sealed position or an open position of the closeable element to an electronic controller, the electronic controller disposed to at least one of provide an indication to an operator and prevent operation of the engine based on the position signal.
 10. The engine system of claim 6, further comprising a pressure sensor disposed to sense and provide a pressure signal indicative of a fluid pressure within the sealed cavity to an electronic controller, the electronic controller disposed to at least one of provide an indication to an operator and prevent operation of the engine based on the pressure signal.
 11. The engine system of claim 6, further comprising: a gas conduit fluidly connecting an internal volume of the compressed gaseous fuel tank with the sealed cavity of the sealable enclosure; and a pressure regulator device disposed to regulate a pressure of fluid passing through the gas conduit; wherein the compressed fluid maintained within the sealed cavity in a pressurized condition during operation of the engine is gaseous fuel vented from the compressed gaseous fuel tank.
 12. The engine system of claim 6, further comprising: an auxiliary air compressor driven by the engine; an auxiliary compressed air tank associated with the engine system; an auxiliary air conduit fluidly connecting the auxiliary compressed air tank with the sealed cavity of the sealable enclosure; and a flow regulator device disposed to regulate a pressure and flow rate of fluid passing through the auxiliary air conduit; wherein the compressed fluid maintained within the sealed cavity in a pressurized condition during operation of the engine is compressed air.
 13. The engine system of claim 6, further comprising: a turbocharger having a turbine and a compressor associated with the engine; a charge air cooler disposed to compress an engine intake charge from the turbocharger compressor; a charge air conduit fluidly connecting an outlet of the turbocharger compressor with the sealed cavity of the sealable enclosure; and a flow regulator device disposed to regulate a pressure and flow rate of fluid passing through the charge air conduit; wherein the compressed fluid maintained within the sealed cavity in a pressurized condition during operation of the engine is compressed air.
 14. A method for preventing contamination of a compressed gas kept in a compressed gas tank with water or other debris entering into the tank through a tank fill port during a tank filling operation, comprising: enclosing a fill port of a compressed gas tank within an enclosure extending around a fill portion of the fill port; pressurizing an internal cavity of the enclosure with fluid; maintaining the internal cavity of the enclosure in a pressurized condition such that ingress of debris into the internal cavity is discouraged; opening the enclosure and depressurizing the internal cavity before carrying out a tank filling operation; closing the enclosure after the tank filling operation is complete; and re-pressurizing the internal cavity of the enclosure with fluid.
 15. The method of claim 14, wherein opening the enclosure includes opening a lid that sealably and releasably engages a wall of the enclosure that surrounds the fill portion of the fill port.
 16. The method of claim 15, further comprising monitoring a position of the lid relative to the wall, and providing a signal indicative of the position of the lid to an electronic controller, wherein the electronic controller is configured to provide a notification to an operator when the lid is in the open position.
 17. The method of claim 14, further comprising monitoring a pressure of the fluid within the internal cavity and providing a signal indicative of the pressure of the fluid to an electronic controller, wherein the electronic controller is configured to provide a notification to an operator when the pressure of the fluid is below a threshold pressure value when the enclosure is sealed.
 18. The method of claim 14, further comprising regulating a pressure of the fluid used to pressurize the internal cavity.
 19. The method of claim 14, wherein the fluid is gas vented from the compressed gas tank.
 20. The method of claim 14, further comprising compressing air in an air compressor and regulating an air pressure of the compressed air, wherein the fluid is compressed air provided to the internal cavity. 